A Simultaneous inversion study was conducted to characterize the sandstone reservoir in the Lower Pematang formation. The elastic parameters that can be generated from the Simultaneous inversion include P-impedance, S-impedance, and Vp/Vs. The results of the sensitivity test on the well data indicate that the Acoustic Impedance and Vp/Vs with the main parameters VCL, porosity and water saturation can separate the lithology well, but not able to separate the fluid due to minimal separation. So in this study, referring to the parameters of the sensitivity test results, an inversion is conducted to separate the lithology and dispersion of the sandstone reservoir based on the Acoustic Impedance (AI) and Vp/Vs. In the high pavement sandstone target reservoir has Vp/Vs value of 1.5-1.8. In the formation of Lower Pematang obtained porosity value ranges between 10% to 18%. This quantitative value can be used as a good reservoir sand scattered also in the well area, while to the west, the porosity value decreases. High porosity values around the well are supported by low values for AI and Vp/Vs.